The present disclosure relates to a multi-part device for separating plasma from whole blood.
Besides centrifuges, which are used mainly in laboratories for separating plasma from whole blood, there are known a number of devices for obtaining very small amounts of plasma at the Point of Care (PoC) by separating plasma from whole blood by means of filtering.
In the simplest case plasma separation may be effected by means of a multilayer test strip as described in U.S. Pat. No. 5,262,067 A (BOEHRINGER MANNHEIM), where a transport layer on an inert carrier layer is provided for transporting sample fluid (whole blood) from an input area to a measuring area. The transport layer may for instance be made of glass fibre mat, which in the input area is covered by a plasma separation layer. The procedure is however only suitable for analysers processing test strips.
From EP 0 550 950 A2 (SANWA KAGAKU KENKYUSHO) there is known a method and a device for separating blood serum and plasma. This document presents diverse variants of devices for plasma extraction, where for instance in FIGS. 1 to 4 variants are described in which a plasma separating device is integrated in a blood sampler. By means of a partial vacuum blood is first sucked into a collector vessel in which there is disposed a two-layer separating filter.
After the blood sample has been taken the collector vessel is connected to an evacuated fluid container, the plasma being separated by the separating filter and collected in the fluid container. In the variant shown in FIGS. 5 and 6 the partial vacuum required for plasma separation is generated by means of a plunger syringe. The variant of FIGS. 9 and 10 furthermore shows a kind of syringe input filter, which may also be used for obtaining plasma.
From WO 96/24425 A1 (FIRST MEDICAL INC.), especially from its FIGS. 1 to 3 and 8, a method and device for plasma separation is known. A device called “Blood Separation Device” comprises a filter element, a flexible tube and at its end a needle which is introduced into a “Blood Collection Device”. By means of a motor unit comprising a peristaltic pump acting on the flexible tube whole blood is sucked from the “Blood Collection Device” and pumped through the filter element, whereby plasma is separated and can be obtained for further use at a plasma output opening of the filter unit. The relatively high uncontrolled pressure values met at the filter unit when pressure is applied and the partial vacuum occurring in the collection vessel when whole blood is continuously sucked off are disadvantageous.
EP 1 469 068 A1 discloses an apparatus for separating and purifying nucleic acids, which comprises a cylindrical syringe having a leading end part in which a first opening part is formed, and an accommodation part being able to hold liquid therein. A solid phase-holding member is connected to the leading end part of the syringe and a flow hole is formed at the leading end side of the solid phase-holding member. A solid phase comprised of an organic polymer having a hydroxyl group on the surface thereof and being able to adsorb and desorb nucleic acids in a sample solution is accommodated in said solid phase-holding member. In the leading end part of the syringe there is formed a liquid-guiding surface of a shape that increases the diameter of the cross section towards the solid phase element. The apparatus can be used for separating and purifying nucleic acids but does not work as plasma separation device.
From U.S. Pat. No. 6,761,855 B1 an improved column for use in solid phase synthesis or purification of complex chemicals, such as biomolecules and more specifically oligonucleotides is known. The column has a top orifice with a sufficient diameter so that a fluid line or a multiple fluid line bundle may dispense fluids into the column with great efficiency. The column has an upper cavity portion configured and sized to render it compatible with dispensing pipettes, so that it can be used as a pipette tip to aspirate the column. The column has a lower cavity portion with a shoulder for ready placement of a lower frit to contain the solid support in a central cavity portion of the column. An upper frit can be conveniently placed in the central cavity portion to seal the solid phase resin. The lower end tip of the column is configured as a Luer-type fitting to provide a male Luer connection. The upper cavity portion is configured to interface with the male Luer of another column, so that two or more columns to be connected in series.
U.S. Pat. No. 4,046,145 B1 shows a connector for joining a small dose syringe to a large reservoir syringe for filling the small dose syringe from the reservoir syringe. The connector has a tubular female-to-female coupler and can be furnished with a filter element. Thus, particulate matter that might be within the large reservoir syringe is filtered out prior to its transfer to the small dose syringe.
It is an object of the present disclosure to propose a device for separating plasma from whole blood, which should be simple and economical to handle and where plasma samples for subsequent application steps may be obtained even from small blood samples and/or samples with high haematocrit values and where these samples may be fed to the input unit of an analyser in a simple way.